Open hearth furnace doors



INVEN R. J. DEMAISON OPEN HEARTH FURNACE DOORS March 19, 1963 5 Sheets-Sheet l Filed Oct. 20, 1959 March 19, 1963 R. J. DEMA'lsoN f 3,081,752

OPEN HEARTH FURNACE nooRs Y INVENTO fly/vwo J 5 A/.sjo/v BY y .WMM/M March 19, 1963 Filed Oct. 20. 1959 R. J. DEMAlsoN 3,081,752

oPEN HEARTH FURNAGE DooRs 5 Sheets-Sheet 3 United States Patent O 3,081,752 OPEN HEARi-l FURNCE DGRS Raymond Il'. Demaison, Bronx, NSY., assigner to Quigley Company, ine., a corporation of New York Filed @ctx 20, 155'9, Ser. No. 847,656 8 Claims. (Si. 122-498) This invention relates to furnace doors for use on open hearth furnaces and in particular relates to the type of door which is water-cooled and contains a refractory material insert or lining.

The principal feature of the invention is to provide a water-cooled open hearth furnace door with a refractory insert made up of a plurality `of blocks or panels which. may be readily removed and replaced. In one embodiment, such removal and replacement may be'elfected from the outside under normal furnace operating conditions without the necessity of removing the door from -the furnace. In another embodiment, the door must be removed from the furnace before the blocks or panels can be removed or replaced but the arrangement is such that the repair operations can be performed expeditiously and without difficulty. v

The present invention therefore contemplates certain improvements in the construction of a water-cooled open hearth furnace door which definitely overcome one of the greatest difculties heretofore encountered in the operation of an open hearth furnace. In addition the method of preforming the refractory blocks or panels without any metal protrusions eliminates the possibility of breakage during shipment arid obviates the necessity of special cratin'g or boxing. Moreover, the inclusion of a metal reinforcing grid with the attaching and supporting means attached thereto and embedded in said blocks or panels insures longer life due to cooler operation with better heat control. The end result is decreased cost of operation due to the longer life span of the refractory blocks or panels and the ease of replacement.

The present invention may be briefly described as comprising a water-cooled open hearth furnace door having a steel shell forming a complete water jacket around the outer edge, said shell defining a rectangular shaped pocket on the furnace side of the door `for the insertion of refractory blocks or panels.

In one embodiment, there are a series of vertical rectangularly shaped water jackets separated by a series of slots or openings which permit the refractory blocks or panels to be `attached and supported in place. 1n this embodiment, it is necessary to remove the door from the furnace in order to replace the refractory blocks or panels but it must be remembered that this replacement is a lot faster than that of the old type of monolithic insert in which the material is hand plastered or sprayed in place layer by layer and then allowed to dry out before use. ln the instant embodiment, it is possible to put in new preformed refractory blocks or panels, bolt them in place in the slots and the door is ready for service again.

In a second embodiment, there are also a series of vertical rectangular shaped water jackets with separating slots for attaching and supporting the preformed refractory lblocks or panels. In this particular instance, the series of vertical water jackets are stopped short of the top shell of the door, leaving a space `for the insertion and removal of -the refractory blocks or panels from the rear. There is a horizontal rectangularly shaped water return passage across the top of the vertical water jackets connecting them to the outlet in order to obtain full cooling of the door. The section of the door above the water jackets is therefore open and constitutes the means by which the refractory blocks or panels may be attached to and supported on the door by the simple method of allowing,T them to slide down into position in the slots and 'then locking them in place. The last row of refractory blocks or panels across the top open space is held in place by means of angle plates secured by cap screws threaded into the top of the water return jacket.

The refractory blocks or panels are preformed of suitaable high heat-resisting refractory materials and have embedded therein suitable metal reinforcing grids with large square nuts attached thereto which serve as the attaching and supporting means by which the refractory blocks or panels -are mounted in the furnace door. The reinforcing and attaching means, in addition, furnish a means for controlling the transfer of heat to the water cooling jackets and thus provide a predetermined heat balance, insuring longer life to the refractory blocks or panels as well as allowing them lto be replaced with a minimum of effort.

It can readily be seen from the above brief description that a new advance has been reached in the design and construction of a water-cooled open hearth furnace door.

Referring to the drawings:

FIG. l is a front elevation of the back side of a Watercooled openhearth furnace door constructed in accordance with the invention and which must be removed from the furnace to replace -the refractory blocks or panels;

FIG. 2 is a horizontal section taken along the lines @-2 of iFIG. 1;

FIG. 3 is a Ifront elevation of the back side of a watercooled open hearth furnace door constructed in accordance with the invention and wherein the refractory blocks or panels may be removed 4and replaced from, the back side through an opening at the top without removing the door from the furnace;

FIG. 4 is a horizontal section taken along the lines 4 4 of FG. 3;

FIG. 5 is a top View of the preformed refractory block or panel with the reinforcing grid with attaching and supporting nut appended thereto therein; and

FIG. 6 -is a side View of the preformed refractory block 0r panel in FIG. 5 and shows the attaching and supporting nut Hush with the back or mounting face.

Before going into a detailed description of the invention being disclosed herein, it may be Well to clarify the front and back sides of the furnace door in order to make the text more readily understandable. The front side of the furnace `door is to Ibe considered the inside which is exposed to the furnace heat while the back side is to be considered the outside which is 'away from the heat and therefore accessible at all times.

The improved furnace `door includes an outer rectangular metal supporting yframe 10 and 'an inner system of preformed blocks or panels 17 which form va facing or lining for the door and which are composed of high temperature resisting refractory material. The frame itl has a back Wall 11 and side walls 13 which form a pocket to receive the preformed blocks.

A jacket 12 extends around the periphery or rim of the supporting Aframe and provides passages 14 for the circulation of water or some other cooling medium therethrough. Additional vertically disposed :and spaced apart water jackets 9 are formed on the outside of the back wall 11 and provide vertical water circulating passages 15 which communicate with the water passages 14 in the top `and bottom portions of the jacket 12. A water inlet pipe 3@ and 'a water outlet pipe 31 are tapped into the top water passage 1d at its opposite ends and `are detachably connected to a suitable supply and drain system by means of couplings.

As clearly shown in FIGS. 1 and 2, the vertically disposed water jackets 9 are spaced apart suliicient to expose the back plate 11 and provide channels affording room for the fastening elements (later to be described) employed in attaching the preformed blocks to the supporting frame. These exposed portions of the back plate il are formed with vertical slots ll through which the fastening elements for the lblocks are passed and which locate the blocks in proper vertical tier formation.

A cylindrical sleeve or thirnble 8 passes through one of the vertical water jackets 9 from one side of the door to the other and forms the customary wicket opening or peep hole for furnace operation observation.

In this embodiment it is necessary to remove the furnace door il() from the furnace in order to effect the removal or replacement of the refractory blocks or panels 17 which lare contained in its front face. It is not necessary to remove the door to some remote spot in order to effect this repair but it can readily be effected in short order right near the furnace. It is desirable to precoat the blocks 17 with a suitable high temperature cement in plastic form in order to bottom and fill the voids between the refractory blocks and when the cement has set sufficiently the seams on the faces of the blocks are cut back a suitable amount to allow the faces of the blocks or panels to expand under the extreme heat without spalling.

Referring now to the second embodiment shown in FIGS. 3 and 4:

In this embodiment, the improved furnace door is substantially the same as the furnace door in the first embodiment described herein, including an outer rectangular metal supporting frame liia having side walls i2@ and ida with a water jacket 14a for the circulation of water or other `cooling medium. in this second embodiment, however, the vertical rectangular water jackets 9a terminate a suitable distance below the top water passage 14a and are connected together by means of another horizontal water jacket `2d which in turn is `connected to the side passages 14a of the water jacket. The opening 22. at the top of the door 10a is of sutiicient height to allow a refractory block or panel 17 to be passed therethrough from the back side for mounting on the front side of the furnace door without removing the furnace door from the furnace. In this second embodiment, also, the horizontal water passage 2l is formed with a series of access holes 23 for the block attaching elements. In addition the top row of refractory blocks or panels in the opening 122` are held in place by means of angles 25 secured to the horizontal water pass-age 21 by means of cap screws 25 and lock washers Z7.

The characteristic feature of both embodiments is that the door facing or lining is in the form of separate preformed blocks or panels which are of uniform size and shape :and which are individually :attached to ,and supported on the water-cooled supporting frame. One of the blocks, designated 17, is shown in FIGS. and 6. It is rectangular in shape and has embedded therein a metal reinforcing grid 28 consisting of two suitably formed metal strips arranged at suitable angles to each other Kand then welded to a large square nut 29 in the zone of intersection. The opposite ends of each strip are bent outwardly from the plane of intersection to provide offsets which extend in the direction of the thickness of the blocks. The outwardly extending offsets are then split centrally and `again bent in reverse directions to provide tabs which extend parallel to the face of the block. The metal reinforcing grid therefore not only affords a good reinforcement for the refractory block but also provides a means for building in a predetermined heat balance to help cool the block.

As will be observed in FIGS. 5 and 6, the large square nut 29 is flush with the outer face of the block and serves as a means for attaching the blocks or panels I7 to the furnace door. Such attachment is effected by a threaded stud 18 screwed into the square nut 29 and passed through one of the lslots 16 or 16a in the back plate il or 11a.

A flat washer 19 is placed on the threaded stud for contact with the back plate lll or 11a and a clamping nut 20 is then screwed onto the threaded stud so as to clamp the block or panel in place. The nuts 2i) are completely housed in the channels formed by the spaces between the water jackets 9 or 9a along the slots :16 or 16a in both embodiments of the invention. The heat transfer in the block or panel is therefore effected Idirectly to the metal supporting frame and thence to the Iwater jackets.

In the second embodiment, as shown in FIGS. 3 and 4, the threaded studs 1S for the top horizontal row of blocks or panels are passed through openings in the vertical portions of the angle plates 25 to which the blocks are anchored through the medium of the washers 19 and clamping nuts Ztl.

In this second embodiment, also, the threaded studs 1S for the diferent vertical tiers of blocks, yare first attached to the blocks and then entered into the vertical slots 16a at the top during assembly'or repair, the slots thus serving as guides for sliding the blocks into land out of place and maintaining them accurately in vertical alignment. By the same token, during the removal of the blocks, the threaded studs may be left attached to the blocks and used as a means for lifting and guiding them out through the opening Z2 at the top while the door remains in furnace operating position or, if the blocks are damaged, they may be knocked out into the furnace area and replaced.

While not necessary, it is desirable, before mounting the blocks or panels in place, to coat the back Side with a suitable high temperature cement in plastic condition in order to provide a perfect bottoming of the panels or blocks as they are bolted in place. It can readily be seen that the faces of the blocks may then readily expand and contract without spalling of the faces.

The use of individual blocks or panels as a refractory facing for the furnace door is highly desirable and yadvantageous, due to the fact that the blocks may be preformed with suitable reinforcing means therein to give structural strength and proper heat control and then readily mounted in place. However, in operation it is quite a frequent occurrence for the refractory facings to become damaged in small areas and in such cases the damage can lbe repaired by simply removing the affected blocks or panels either singly or in tiers and replacing them with new ones.

Any suitable high temperature refractory material may be used for the preformed blocks or panels, but the one which is preferred is chrome-magnesium. The high temperature refractory material that is preferred for lattaching and supporting the blocks in place is Roofchrorne in a plastic condition.

-It can now be readily seen by those skilled in the art that the invention disclosed herein represents a great ad- Vance in open hearth furnaces. Furnace doors have always been a major repair problem as they could only be repaired in the past by removing them from the furnace and transporting them to the repair shop, necessitating the installation of a new door. With this invention, the doors may be easily and quickly repaired, thus saving a great deal of time and labor in the operation of the furnace and in obviating the necessity of having large areas for door repairs.

What is claimed is:

1. An open hearth furnace door comprising a metal' supporting frame faced on its front side with a series of separate preformed unit-ary blocks or panels of refractory material havin-g uniform size and shape, said blocks or panels being arranged in a plurality of vertical tiers and having their opposite ends disposed in flush rel-ation in vertical parallel planes, Ia single fastening means, one for each block or panel located centrally thereof, for individually attaching it and individually detaching it from the metal supporting frame, said single fastening means having one portion embedded immovably in its block or panel `as preformed and comprising a metal reenforcement grid andan anchor element attached rigidly thereto, both the grid and the anchor element being located within the confines of the block or panel, and said single fastening means having a second portion exterior of the block or panel :and comprising a frame engaging element dstinct from the anchor element of the embedded portion, but attachable thereto and detachable therefrom from the back side of the furnace door, said metal supporting frame including means forming a plurality of vertically disposed openings to accommodate the exterior portions of the fastening means and located midway between the ends of the blocks or panels in the respective vertical tiers to accord with the `central location of the fastening means in said tiers, `and ya series of vertically `disposed cooling medium jackets onthe back side thereof, spaced apart to form channels between Iadjacent jackets along said openings completely housing said frame engaging elements.

2. An open hearth furnace door according to claim 1, wherein the anchor element yconsists of a nut accessible through the `corresponding opening in the metal supporting frame.

3. An open hearth furnace door according to claim 2, wherein said exterior portion of the fastening means includes a threaded stud projecting through said corresponding opening and screwed into the nut embedded in the corresponding `block or panel.

4. An open hearth furnace door according to claim 3, wherein said frame engaging element is a clamping nut screwed onto the exposed end of the threaded stud to lock the corresponding preformed block or panel in place onto the metal supporting frame.

5. An open hearth furnace door comprising a metal supporting frame faced on its front side with a series of separate preformed unitary blocks or panels of refractory material having uniform size and shape, said blocks or panels being arranged in a plurality of vertical tiers and the blocks or panels in each tier having their opposite ends disposed in flush relation in vertical parallel planes, a lsingle fastening means, one for each block or panel located centrally thereof, for individually attaching it and individually detaching it from the metal supporting frame, said single fastening means having one portion embedded immoVa-bly in its block or panel as preformed and comprising a metal reenforcement grid and an anchor element attached rigidly thereto, both the grid and anchor element being located within the contines of' the block or panel, and said single fastening means having a second portion exterior of the block or panel and comprising a frame engaging element distinct Vfrom the anchor element of the embedded portion but attachable thereto and detachable therefrom from the back side 0f the `furnace door, said metal supporting frame having means forming a plurality `of vertically disposed slots in the metal supporting frame open at the top to accommodate the exterior portions of the fastening means and located midway between the ends of the blocks or panels in the respective tiers to accord with the central location of the fastening means in said tiers, said frame also having means forming a horizontal space at thetop of said frame extending across all of the vertical tiers of lblocks or panels and having a vertical dimension great enough to accommodate a block or panel of any tier, said space communicating with the open top ends of the vertical slots and open at the back side of the door so as to permit the exterior portions of the fastening means to enter or leave the slots in attaching or detaching the Iblocks or panels While the door is in operative position.

6i. An open hearth furnace door according to claim 5, wherein the horizontal space is filled with a horizontal -row of preformed blocks or panels.

7. An open hearth furnace door according to claim 6, wherein the prefonmed blocks or panels which lill the top horizontal space are individually secured in place by angle pieces attached at one end to the blocks or panels and at the other end to the metal supporting frame.

y8. An open hearth furnace door `according to claim 5, wherein the .metal supporting frame is jacketed for the circulation of a cooling medium therethrough.

References Cited in the le of this patent UNITED STATES PATENTS 1,072,857 Kickert Sept. 9, 1913 2,395,757 Peters Feb. 26, 1946 2,405,610 Sampson Aug. 13, 1946 2,512,439 Richards lune 20, 1950 2,664,838 Sorensen Ian. 5, 1954 OTHER REFERENCES Industrial Furnaces, volume 1 (Trinks), published by John Wiley and Sons (New York), 1934r (page 398 relied on). 

1. AN OPEN HEARTH FURNACE DOOR COMPRISING A METAL SUPPORTING FRAME FACED ON ITS FRONT SIDE WITH A SERIES OF SEPARATE PREFORMED UNITARY BLOCKS OR PANELS OF REFRACTORY MATERIAL HAVING UNIFORM SIZE AND SHAPE, SAID BLOCKS OR PANELS BEING ARRANGED IN A PLURALITY OF VERTICAL TIERS AND HAVING THEIR OPPOSITE ENDS DISPOSED IN FLUSH RELATION IN VERTICAL PARALLEL PLANES, A SINGLE FASTENING MEANS, ONE FOR EACH BLOCK OR PANEL LOCATED CENTRALLY THEREOF, FOR INDIVIDUALLY ATTACHING IT AND INDIVIDUALLY DETACHING IT FROM THE METAL SUPPORTING FRAME, SAID SINGLE FASTENING MEANS HAVING ONE PORTION EMBEDDED IMMOVABLY IN ITS BLOCK OR PANEL AS PREFORMED AND COMPRISING A METAL REENFORCEMENT GRID AND AN ANCHOR ELEMENT ATTACHED RIGIDLY THERETO, BOTH THE GRID AND THE ANCHOR ELEMENT BEING LOCATED WITHIN THE CONFINES OF THE BLOCK OR PANEL, AND SAID SINGLE FASTENING MEANS HAVING A SECOND PORTION EXTERIOR OF THE BLOCK OR PANEL AND COMPRISING A FRAME ENGAGING ELEMENT DISTINCT FROM THE ANCHOR ELEMENT OF THE EMBEDDED PORTION, BUT ATTACHABLE THERETO AND DETACHABLE THEREFROM FROM THE BACK SIDE OF THE FURNACE DOOR, SAID METAL SUPPORTING FRAME INCLUDING MEANS FORMING A PLURALITY OF VERTICALLY DISPOSED OPENINGS TO ACCOMMODATE THE EXTERIOR PORTIONS OF THE FASTENING MEANS AND LOCATED MIDWAY BETWEEN THE ENDS OF THE BLOCKS OR PANELS IN THE RESPECTIVE VERTICAL TIERS TO ACCORD WITH THE CENTRAL LOCATION OF THE FASTENING MEANS IN SAID TIERS, AND A SERIES OF VERTICALLY DISPOSED COOLING MEDIUM JACKETS ON THE BACK SIDE THEREOF, SPACED APART TO FORM CHANNELS BETWEEN ADJACENT JACKETS ALONG SAID OPENINGS COMPLETELY HOUSING SAID FRAME ENGAGING ELEMENTS. 